A substantial amount of research and development is presently being carried out for the purpose of producing practical and economical photovoltaic generating units. In general, photovoltaic generating units, as presently contemplated, will comprise a multiplicity of individual photovoltaic generating modules, each of which contains a plurality of individual photovoltaic cells. The modules are connected to each other in accordance with a predetermined wiring arrangement to produce electrical power at the main output terminals of the array of modules. The precise circuit arrangements employed will depend upon a number of considerations, such as the size of the system, the voltage desired at the output terminals of the system, and the nature of the installation, for example, whether the installation is provided on the roof of the building or on a support specifically constructed for the generating unit.
The electrical connections in the system between and among the modules is an important factor in the practicality of the system. The connections should be of reasonable cost, should be sealed against the elements, and should be of a nature such that the connections can be made by a mechanic of ordinary skill. It is also important that the generating unit, as a whole, be serviceable in the sense that individual modules can be removed for replacement or repair without disassembling the entire system. The present invention in accordance with one aspect thereof is directed to the achievement of improved photovoltaic modules which can be connected into the electrical network of a photovoltaic array with relative ease and which will satisfy all the requirements of the electrical connections for such systems.
One type of photovoltaic module presently being developed and tested is in the form of a roof shingle having an active portion in which the photovoltaic cells are positioned, and an inactive portion which partially surrounds the active portion. Shingles of this type are installed on a panel such as the roof of a building, in much the same manner as are ordinary shingles, and the photovoltaic shingles perform, in part at least, the ordinary functions of shingles as well as a photovoltaic function. In the installation of shingles on a building roof, it is therefore necessary to connect the terminals of the active portions of the shingles into the electrical network of the system and the technician installing the shingles must therefore make the electrical connections while the shingles are being installed. The electrical network for a photovoltaic system of this type may take different forms, as mentioned above, depending upon circumstances of use and other factors. In any event, it is desirable that the shingles be such that they can be connected in series with each other, in parallel, and in a wide variety of series-parallel combinations. The overall invention, in accordance with a further aspect thereof, is directed to the achievement of an improved photovoltaic shingle module and its methods of installing such modules on a surface to achieve a predetermined wiring arrangement for the modules.
A photovoltaic shingle in accordance with the invention has leads extending from its positive and negative terminals in the form of flat flexible ribbon-like conductors encased in suitable insulating plastic film. The conductors are of the type which can be connected to similar conductors by means of crimpable electrical connecting devices which, when crimped onto two such conductors, are flat and relatively thin. The individual shingles or modules can be connected to each other in series in the array of shingles by simply connecting the negative lead of each shingle to the positive lead of an adjacent shingle, or the shingles can be connected in parallel by connecting the negative and positive leads of shingles positioned in a column to two spaced-apart connecting conductors previously installed on the roof. In either event, bus conductors are provided to which all of the shingles are connected and which extend to a terminal area for the entire system.
The shingles are secured to the roof or other surface by means of fasteners which extend through oversize washers which are positioned against openings in the inactive portions of the shingles. The openings in the shingles have diameters greater than the diameters of the fasteners so that upon removal of the washers associated with an individual shingle, the shingle can be moved away from the fastener and the individual shingle can then be removed from the array for servicing or replacement.